linux-kernel - Re: [PATCH 2/2] drm/amdgpu: Bypass resizing bars for PVH dom0

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Message-ID: <e6dd8f17-2322-4fd7-bdcd-861e77fcfc8a@gmail.com>
Date: Tue, 5 Nov 2024 14:42:47 +0100
From: Christian König <ckoenig.leichtzumerken@...il.com>
To: Jiqian Chen <Jiqian.Chen@....com>,
 Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>,
 Xinhui Pan <Xinhui.Pan@....com>
Cc: amd-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@....com>,
 Huang Rui <Ray.Huang@....com>
Subject: Re: [PATCH 2/2] drm/amdgpu: Bypass resizing bars for PVH dom0

Am 05.11.24 um 07:05 schrieb Jiqian Chen:
> VPCI of Xen doesn't support resizable bar. When discrete GPU is used on
> PVH dom0 which using the VPCI, amdgpu fails to probe, so we need to
> disable this capability for PVH dom0.

What do you mean VPCI doesn't support resizeable BAR?

This is mandatory to be supported or otherwise general PCI resource 
assignment won't work either.

In other words you can't hotplug something if that here doesn't work either.

Regards,
Christian.

>
> Signed-off-by: Jiqian Chen <Jiqian.Chen@....com>
> Reviewed-by: Huang Rui <Ray.Huang@....com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index b3fb92bbd9e2..012feb3790dd 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -1619,6 +1619,10 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
>   	if (!IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT))
>   		return 0;
>   
> +	/* Bypass for PVH dom0 which doesn't support resizable bar */
> +	if (xen_initial_domain() && xen_pvh_domain())
> +		return 0;
> +
>   	/* Bypass for VF */
>   	if (amdgpu_sriov_vf(adev))
>   		return 0;